Skin color is largely determined by a melanin amount, hemoglobin, carotene, and the like, and among them, melanin plays the most important role. Melanin determines the skin color of a person and also serves to protect the skin; however, when melanin is excessively produced in the skin by changes in external environment such as overexposure to ultraviolet light, air pollution, stress, and inflammation, pigmentation occurs, resulting in dark skin color or causing spots or freckles. Among the external stimulating factors, ultraviolet light is the strongest stimulus of melanin biosynthesis and may affect various processes related to melanin production. That is, ultraviolet light acts as a main factor for inducing overproduction of melanin by promoting activity of melanocytes which are melanin-producing cells, promoting secretion of a melanocyte-stimulating hormone, promoting oxidation of melanin, promoting tyrosinase activity, and the like.